As devices which produce printed circuit boards on which multiple components are mounted, there are solder printers, component mounting machines, reflow ovens, printed circuit board testers, and the like, and these are often linked to form a printed circuit board production line. Of these devices, component mounting machines are generally provided with a board conveyance device, a component supply device, and a component transfer device. The board conveyance device performs the loading, unloading, and positioning of the printed circuit board. The component supply device sequentially supplies components of multiple types to a predetermined supply position. The component transfer device is provided with a board camera which images a positioned printed circuit board, a suction nozzle which picks up and holds a component from the component supply device using negative pressure and mounts the component to the printed circuit board, and a head drive section which drives a mounting head which holds the board camera and the suction nozzle.
In order to mount a component at a predetermined mounting point on a printed circuit board, generally, fiducial marks on the positioned printed circuit board are imaged and the positioning error is corrected in advance. Accordingly, it is possible to accurately perform positional control of the suction nozzle to the mounting point using coordinate values on the printed circuit board. However, in a solder printer, when printing solder paste on a land (a part of a circuit pattern onto which leads of a component are soldered) corresponding to the mounting point, the printing may shift for some reason and the solder position may deviate from the center of the land. In this case, when performing positional control based on the coordinate values, if the actual mounting point of the component is the center of the land, the mounting point deviates from the center of the solder position. Therefore, an adverse effect arises in that the component is pushed out from the center of the land, which is the original mounting point, and falls over and so on by the solder, which is remelted in the reflow oven, flowing to the center of the land.
A technique of TOP (Target On Paste) mounting has been developed in order to prevent the adverse effect caused by the print shifting of the solder paste described above. In TOP mounting, the solder position at which the solder paste is actually printed is detected, and mounting is performed after correcting the coordinate values of the mounting point of the component accordingly. Therefore, a self alignment effect is obtained in the reflow oven. In other words, the component which is mounted at the center of the solder position is automatically subjected to positional correction to the vicinity of the center of the land, which is the original mounting point, by the flowing of the remelted solder. Examples of techniques which enable the detection of the printed solder position by image processing in order to perform the TOP mounting are disclosed in PTL 1 and PTL 2.
A three-dimensional measurement device of PTL 1 is provided with means for irradiating a measurement target with a striped light intensity light pattern containing multiple wavelength components, a means for separating the reflected light from the measurement target for each wavelength component, imaging the separated result, and acquiring the image data, a means for changing a relative phase relationship between the measurement target and the light pattern, and a means for calculating the height of the measurement target based on multiple items of image data under multiple relative phase relationships. Accordingly, it is considered possible to greatly improve the measurement precision with regard to the calculated height. Note that, the embodiment discloses a mode in which solder paste which is formed by printing on a printed circuit board is subjected to three-dimensional measurement and quality determination is performed.
A screen printer of PTL 2 is provided with a monochrome imaging means for imaging an inspection target region on a printed circuit board, onto which solder has been transferred, from vertically above, a first lighting means for irradiating the inspection target region from vertically above, a second lighting means for irradiating the inspection target region from diagonally above, a means for obtaining a first image in which a land appears due to the first lighting means and obtaining a second image in which the land and solder appear due to the second lighting means, and a means for obtaining an image in which the first image is subtracted from the second image to depict the solder. Accordingly, it is considered possible to obtain an image in which only the solder is depicted using a low cost monochrome camera.